Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability, etc. Internet Protocol (IP)-based LLNs in a “route-over” configuration define a link-local scope to be those nodes reachable using a single link transmission (e.g., wireless/radio or power-line communication, “PLC”). In cases where multiple radio transmission are required to reach a destination, all routing and forwarding occurs at the network layer using IP.
Devices in an IP-based mesh network, like any other IP network, require a certain amount of network- and application-layer configuration when joining a network. Such configuration information may include IP address assignment, Domain Name Services (DNS) server addresses, IP prefix delegation, etc. The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) (generally described and known in the art through the Internet Engineering Task Force (IETF) “RFC 3315”) provides a standard way to distribute configuration information to devices across a network. DHCPv6 may be used in a stateless configuration where parameters are distributed to requesting clients without maintaining per-client state (e.g., DNS server addresses). DHCPv6 may also be used in a stateful configuration where parameters are selected specifically for each requesting client and the server must maintain per-client state to remember what values were provided to which client.
In a route-over LLN, it is infeasible to place DHCPv6 servers within link-local scope of all devices in the LLN. Doing so would require all nodes to perform DHCPv6 Prefix Delegation, which would unnecessarily divide up the address space across all devices and make assumptions on the number of devices they can assign address too. In s particular, the challenge with DHCPv6 is that it was fundamentally designed for Ethernet-like networks (e.g., Switched Ethernet, IEEE 802.11, etc.) that provide significant communication resources (e.g., large channel capacity, high throughput, efficient broadcast communication, etc.). In particular, DHCPv6 requires the use of link-local multicast to discover neighboring DHCPv6 Relay Agents or Servers. For example, DHCPv6 clients must transmit a Solicit message to a link-local multicast address. A device in a typical Smart Grid deployment may have hundreds of neighbors and a single Solicit message may cause hundreds of responses from neighboring devices.